Permanent-magnet steel



Patented July 24, 1928.

UNITED STATES PATENT oFFipE.

PORTER HQ BRACE, F PITTSBURGH, 'PENNSYLVENIL, ASSIGNOR TO WESTINGHOUBI ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 01 PENNSYLVANIA.

PERMANENT-MAGNET STEEL.

No Drawing.

My invention relates to magneti materials and more particularly to permanent-magnet steels, and it has for its primary object the provision of a permanently magnetizable steel which may be manufactured at a cost materially below that of steels of that character, heretofore known.

\ A further object of my invention'resides in the provision of a magnetizable steel," or steel alloy, which shall be superior to those heretofore known, in that it shall have less tendency to crack while hardening during its manufacture and during heat treatment.

I have found, as a result of investigating the magnetic properties of steel, that the addition of cobalt and one or more ofthe metals of the chromium group, orvanadmm to steel, produces an allo having charabter istics which make it wel suited for use in the manufacture of permanent magnets. While the metalor metals of the chromium group to be employed with the cobalt may,

i preferably, be varied to suit slightly different requirements of use, I have vfound and of the chromium or other metal or minor impurities, are particularly desirable.

that, from standpoints. of cost and general utility, a chromium-cobaltsteel is usually to preferred.

Although the proportions of the cobalt metals of the chromium group, such as molybdenum and tungsten, to be employed may likewise be. varied to suit different conditlons, it is preferable, from the viewpoint of economy, if for no other reason, that the q fintities of such metals be as small as possi e. ranging from 1% to 10% cobalt, 1% to 10%- chromium, and the remainder iron and Previous to this,tungsten steels have been the most extensively used of all steel alloys, or equivalent metals, in the manufacture of permanent magnets and, when properly hardened, such stelsvshow, under suitable tests, the following magnetic characteristics! Maximum induction 16,00017,000 Remanent induction 7,300 7,600 Coercive force 84- 86 lu comparison. with these characteristics, I have obtained the following results from I have found that steel compositions Application filed January 16,1919. Serial'lio; 871,480.

similar tests made with chromium cobalt steels:

Maximum induction 17,00018,000 Remanent induction 7 ,300- 7,500

Coercive force 81. 86

While the quantities of both thecobalt and the chromium or other metal of the chromium group or an equivalent mixture of such metals may vary, the followin tables give two characteristic analyses 0 chromium-cobalt steels which have been found to be "satisfactory;

Cr 5' 3.11 00. 5.00 ass o 0.53 0. 77 Mn 0.00 0.18 r 0.025 0.02 S t 0.013 0.02

The'remainder Fe and minor impurities.

Through actual experience in making steel, alloys 0 the above described character, I have found -that, .during the hardening of the molten alloy and its subsequentheattreatment, there is much less tendency to cracking than is the case with thetungsten steelspreviously used. The heat treatment.

the influence'of a magnetic field for a few moments, as, for} example, by passing an electric current through an insulated wire wrapped around the body to be magnetized,

as is well known in the art.

Heat'treatment ofsteels to be utilized in the making of: magnets and thepro'cess of makin'g magnets therefrom are well known to "metallurgists and are fully described in the. literature of this art, See, for example,

4130f the 1908 edition of the Metal-.

lur of Iron and Steel by Bradley Stoughton'. As it is obvious that cobalt-chromium the iron employ'edQ'may be made within suitable bounds For example, the proportions of the cobalt maybe substantially increased. An alloy containing of a mix- 20 ture of cobalt and chromium and the remainder iron and minor impurities has been found satisfactory. It will, therefore, be

chromium, molybdenum, tungsten and vanal). A magnetized member comprising 1% to 10% chromium, 1% to 10% cobalt and the remainder iron and minor impurities.

4. A chromium-cobalt steel for permanent magnets. x

5. A magnetized member comprising from 2% to 20% of-a mixture, of chromium and cobalt and the remainder iron, carbon and minor impurities.

6. A magnet containing 1% to 10% cobalt and 1% to 10% of at leasttone metal ofthe chromium group.

7 A magnet containing 1% and 1% to 10% chromium.

8. As a new article of manufacture, a magnetized body of an alloy steel containing cobalt and a metal of the chromium group.

9. As a new article of manufacture, a

magnetized body of an alloy steel containto 10% cobalt understood that, when economic conditions ing cobalt and tungsten.

permit, a much higher alloying ingredients may be employed and -'this is especially true of cobalt, the. proportions of whichmay be varied within a com aratively wide range. I do not wish, thereore to, in anyway, restrict my invention to the employment of any particular metals or to the use of any specific proplortions but reboth in materials employed and g in proportions utilized, which may come within the scope of the appended claims. i

I claim as my invention: ,1. A magnetized member comprising substantially 1% to 10% cobalt, 1% t 10% of a metal of the chromium group and the re mainder iron and minor impurities. 2. A magnetized member comprising substantially 1% to 10% cobalt,.1% to 10% of at least one of the following metals:

percentage of the 10. As a" new article of manufacture, a permanent magnet comprisinga magnetized body of an alloy steel containing asubstantial percentage ofcobalt substantially uniformly distributed therethrough.

11. As a new article of manufacture, a

magnetized body of an alloy "steel containing cobalt and chromium;

12. Asa new article of manufacture, a

magnetized body of an alloy steel contain ing cobalt and molybdenum.

13. cobalt, at least one of the following metals; chromium, molybdenum, tungsten, and vanadium, and the remainder iron carbon and minor impurities.

subscribed any name A' magnetized member comprising In teshmony whereof, I- have hereunto this- 31st day. of. Dec., 

